Correlation between locomotion speed and hippocampal theta activity of mice in a virtual corridor

Abstract

In the hippocampus of rodents during locomotion, 5-12 Hz oscillatory EEG (theta activity) is observed. The hippocampal theta activity plays important role in encoding the animal's position during spatial navigation. It has been reported that frequency and amplitude of the theta activity correlate with the locomotion speed. However, the precise temporal relationship has not been elucidated. To investigate the relationship, we recorded the hippocampal EEG from mice during voluntary locomotion in a virtual corridor. It was confirmed that the hippocampal theta activity occurred during locomotion and its frequency and amplitude positively correlated with the locomotion speed. Time-shift cross-correlation analysis revealed that the change in theta activity was approximately 200 ms ahead to that of locomotion speed. Impact of manipulation of visual feedback to the theta activity was not strong. These results suggest that the hippocampal theta activity is forecasting or attracting instantaneous behavior of the animal.